Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

The largest burial mound in the United States holds the remains of prehistoric West Virginians.

A particularly creepy abandoned hospital that sparks interest for lovers of the supernatural.

A model of a dinosaur that was named for Andrew Carnegie stands outside the museum that also bears his name.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

Nassau Hall has served as army barracks, a museum, and played a key role in the American Revolution.

This campus chapel is Robert E. Lee's final resting place and a topic of debate about the legacy of the Civil War.

The land is home to swimming ponies and a legendary 18th-century treasure.

This rural community has attracted both scientists and techno-refugees due to its federally-mandated lack of technology.

This Philly landmark has a giant butterfly pavilion, three floors of insect displays, and withstood a $40,000 heist.

Two gems of Beaux Arts architecture that have been sitting vacant for years.

An Olympic hero stripped of his medals is buried in a town he never visited, which took his name after his death.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

The famous bell was secreted away and hidden in a church in Allentown during the British occupation of Philadelphia.

The sounds of the world's largest fully functioning pipe organ dazzle shoppers at a Philadelphia Macy's.

The first American department store, and home to the largest operating musical instrument in the world.

This elaborate towering structure was once famed for its revolutionary height.

Dr Barnes' $25 billion private collection of art and arboretum.

This Philly cemetery is the eternal home of many famous area residents, including Rocky Balboa's wife.

This little-known collection holds everything from "Dracula" notes, to the manuscript of "Ulysses," to the forged works of Shakespeare.

Yo, Adrian!

One of the oldest surviving Swedish-American homes in the United States.

This splendid Versailles-inspired mansion has the largest French-style formal gardens in North America.

This palatial botanical garden is home to one of the largest pipe organs ever installed in a private residence, and a piece of Wood's cycad.